This application is based on application No 98-12660 filed in the Korean Industrial Property Office on Apr. 9, 1998, the content of which is incorporated hereinto by reference.
(a) Field of the Invention
The present invention relates to a method for producing supported metallocene catalyst and an olefin polymerization process using same, and more particularly to a method for manufacturing supported metallocene catalyst by reacting metallocene catalyst having a hydrocarboxy silane group at a part of a ligand with a support having a highly reactive siloxane group at the surface, and the olefin polymerization process using the same.
(b) Description of the Related Art
In 1976, Professor Kaminsky of Germany reported that olefin polymerization could be made by using MAO (methylaluminoxane) compound obtained through partial hydrolysis of trimethylaluminum as a cocatalyst and by zirconocendichlodide compound as a catalyst (A. Anderson, J. G. Corde. J. Herwing, W. Kaminsky, A. Merk, R. Mottweiler, J. Pein, H. Sinn, and Vollmer, Angew. Chem, Int, Ed. Engl., 15, 630, 1976). This homogeneous catalyst shows unique polymerization characteristics that conventional Ziggler-Natta catalysts can not embody. That is, molecular weight distribution of the produced polymer is narrow, copolymerization is easy, and the second monomer distribution is uniform. Not only molecular weight or the degree of copolymerization can be changed freely by simply changing the catalyst ligand structure, but also tacticity of polymer can be controlled according to the molecular symmetry of catalyst. These unique characteristics not only opened up a way of new polymers not obtainable through conventional Ziggler-Natta catalyst, but also the way of tailor-maid polymers. Accordingly, studies on this catalyst have been actively going on.
Polyethylene manufacturing processes are can be classified into the high pressure process, the solution process, the slurry process, and the gas phase process. Efforts to replace only the catalysts of these processes with metallocene catalysts are being made. In the gas phase or slurry processes, particle morphology and bulk density of the produced polymer should be controlled to increase output per reactor unit capacity, and a reactor fouling should be solved for the continuous operation. In order to increase the bulk density and to solve the reactor fouling, supported catalyst should be used in those process. As a result of this, various efforts to support metallocene catalyst on suitable solid material have been made.
One of the supporting methods of the metallocene catalyst is to synthesize metallocene compounds having functional groups such as alkoxysilaone group on a part of a ligand and then to react these functional groups with hydroxyl group of the silica (R. Jackson, J. Ruddlesden., and D. J. Thompson, J. Organomet. Chem. 125 (1997), 57; B. L. Booth, G. C. Offumme, C. Stacey, and P. J. T. Tait, J. Organomet. Chem. 315 (1986), 145; European Patent No. 293815). In this case, using silica OH group according to such a reaction is plainly stated in the below reaction formula 1. European Patent No. 293815, page 5, lines 11 to 15 describe that support having an amount of hydroxyl group on its surface of 0.5 xcx9c50 mmol/g, particularly 1xcx9c20 mmol/g, and more desirably 1.5xcx9c10 mmol/g, is used.
 less than Reaction Formula 1 greater than 
However, when the compounds are reacted with the hydroxy group of the surfaces, the following various side reactions can be accompanied (D. J. Cardin, M. F. Lappert, and C. L. Raston, Chemistry of Organo-Zirconium and Hafnium Compounds, John Wiley and Song 1986, 96 page).
 less than Reaction Formula 2 greater than 
Cp2ZrCl2+ROHxe2x86x92Cp2ZrCl(OR), Cp2Zr(OR)2, CpZr(OR)3
There is a sufficient possibility that this kind of reaction could also occur when the metallocene compounds are reacted with the silica having hydroxyl group. This kind of side reaction could cause process problems during the polymerization reaction as it could possibly be leached out, when it was activated with aluminoxane. The polymer may show different characteristics from the one obtained from non-supported catalyst, thus losing advantages obtainable by a supported catalyst system.
It is an object of the present invention to provide a method for manufacturing a supported metallocene catalyst by reacting metallocene compounds having an alkoxysilane group with highly reactive siloxane groups, which are produced when the supporting materials are dried at high temperature as in the reaction formula 4, not with OH groups of the supporting materials.
By using this method, supporting materials having much less amount of surface hydroxyl groups should be used in order to eliminate the various side reactions caused by hydroxyl groups.
Also in accordance with the present invention, there is provided a method of manufacturing a supported metallocene catalyst. The method includes the step of reacting a silica with using a metallocene catalyst having an alkoxysilane group. The silica has siloxane groups with high activity on the surface thereof by drying a silica at a temperature above 600xc2x0 C.
Still further in accordance with the present invention there is provide a method of polymerizing olefinic monomer. The method includes the step of polymerizing olefinic monomers by using a supported metallocene catalyst and a cocatalyst. The supported metallocene catalyst is prepared by reacting a silica with a metallocene catalyst having an alkoxysilane group. The silica has siloxane groups with high activity on the surface thereof by drying a silica at a temperature above 600xc2x0 C.
 less than Reaction Formula 4 greater than 